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Long Weld Neck Flanges

High-pressure pipelines with thermal expansion often suffer joint misalignment or weld failures near vessel nozzles. Our Long Weld Neck Flanges eliminate such risks through extended hub length and integral weld design. 

Standard Specification

ASME B16.5, ASME B16.47 Series B, API 605, MSS SP-44

Pressure Rating

Class 150 to 2500 (PN10 to PN420)

Material

Carbon Steel (ASTM A105), Stainless Steel (A182 F304/F316), Alloy Steel (A694 F52/F60)

Nominal Size

½” to 60″ (DN15 to DN1500

Flange Type

Long Weld Neck (LWN) – Extended tapered hub
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Product Description

These flanges maintain axial support under thermal loads, making them suitable for both vertical and horizontal stress zones. We supply sizes up to 60 inches with optional cladding, custom hub length, and international pressure ratings. 

Facing Type

Raised Face (RF), Ring-Type Joint (RTJ)

Dimensions

Hub length 2-3x standard WN flange [Custom lengths available]

Bolt Circle Diameter

ASME B16.5/API 605 standards

Number & Size of Bolt Holes

4 to 48 holes (½” to 1¼” bolts)

Surface Finish

Machined (63-125 μin RA) [RTJ grooves precision-cut]

Corrosion Resistance

Clad versions available (CS body with SS/Alloy 625 weld overlay)

Temperature Rating

-196°C to +650°C [Cryogenic to high-temp applications]

Material Certification

NACE MR0175/ISO 15156, PED 2014/68/EU, EN 10204 3.1

Gasket Compatibility

RTJ gaskets (oval/octagonal), Spiral-wound

Coating/Plating

FBE coating, Inconel weld overlay

Manufacturing Method

Forged (ASTM A182) + CNC machining [Integral hub design]

Technical Advantages

Sudden flange failure in high-stress pipelines can lead to shutdowns or leakage. Our Long weld neck flanges maintain axial strength with their integral neck and longer weld zones. 

Each piece undergoes CNC machining for accurate face alignment and bolt circle positioning. Available options include RTJ groove cutting, Inconel overlay, and PED/NACE certified material traceability. 

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Industry Applications

Pressure Vessel Nozzle Connections

Links nozzles to high-pressure vessels in process plants with reduced stress risers and stable weld zones.

Heat Exchanger Inlet/Outlet

Serves as a secure transition between exchanger shells and process piping under fluctuating temperature ranges.

LNG and Cryogenic Systems

Handles extreme contraction with extended hubs and tested weld integrity from -196°C operation onwards.

Power Plant Steam Lines

Used in boiler feed and turbine lines where flange-to-pipe misalignment affects long-term reliability.

Petrochemical Reactors

Withstands aggressive pressure cycling and chemical exposure without losing gasket seating force. 

Desalination Brine Discharge

Installed in high-flow seawater discharge pipelines where flange performance must remain consistent under vibration.

Weld Integrity with Dimensional Control

Mismatch during field welding often adds cost and delay during large-bore flange installation. We supply Long weld neck flanges with machined hub faces, uniform thickness, and drawing-based bolt hole alignment. 

This simplifies site fitting while maintaining flange pressure ratings across Class 150 to 2500. You receive repeatable quality with packaging support for coated or cladded versions. 

long neck weld flanges

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Having Doubts? Our FAQ

Check all our Frequently Asked Question

Can I request a specific hub length based on nozzle design?

Yes, we support hub lengths beyond standard values based on your drawing or design conditions. This helps reduce stress concentration and aligns with vessel nozzle geometry. Custom lengths go through drawing approval before production.

Do you offer weld overlay options for corrosive service?

Yes, we provide cladding options like Inconel 625 or stainless overlays on carbon steel bodies. This ensures chemical resistance without sourcing full alloy flanges. All overlays follow ASME Section IX welding procedures. 

Will your Long weld neck flanges fit non-standard bolt circles?

We can match bolt hole count, pitch, and diameter to your drawing even outside ASME/API ranges. This allows direct replacement or connection to custom equipment. Each piece is CNC drilled with verified layout sheets.

How do you verify flange performance under thermal load?

We use FEA-backed hub profiles and control grain flow during forging to avoid thermal distortion. Machining maintains neck concentricity to prevent flange tilt during welding. Each flange undergoes PMI and dimensional check before dispatch.

Do you support third-party inspection before shipment?

Yes, we welcome customer-nominated inspectors during final QC. Our inspection plans include UT, hardness, and face flatness tests. Certificates are issued as per EN 10204 3.1 or 3.2 formats.

Are bulk orders supported for project-based procurement?
  • Frigate supports bulk and project-scale manufacturing for EPC contractors and OEM clients 
  • In-house production planning ensures consistent lead times across multiple batches 
  • Full batch traceability maintained through controlled manufacturing processes 
  • Dispatch schedules aligned with project execution and site requirements 
Can pricing be provided based on custom drawings and specifications?
  • Frigate prepares quotations based on submitted GA drawings and technical specifications 
  • Cost structure includes material grade, machining scope, overlays, and inspection requirements 
  • Engineering team provides value optimization inputs for cost-effective manufacturing 
  • Fast RFQ turnaround supports time-bound procurement cycles 
What is the typical manufacturing lead time?
  • Frigate delivers standard sizes within 2–4 weeks depending on volume 
  • Custom or cladded flanges manufactured within 4–8 weeks based on complexity 
  • Expedited production supported for shutdown and critical applications 
  • Confirmed timelines shared with structured production milestones 
Is export-grade packaging available for shipment?
  • Frigate provides seaworthy wooden packaging for international shipments 
  • Flange faces protected with caps and anti-corrosion coatings 
  • Additional handling and protection applied for cladded or overlay components 
  • Custom marking, tagging, and documentation included as per project specifications 
How is consistency maintained across repeat orders?
  • Frigate follows controlled forging and CNC machining processes for repeatability 
  • BOM-driven manufacturing ensures alignment with approved drawings and specifications  
  • Inspection reports and dimensional records maintained for future reference 
  • Dedicated quality control ensures uniform performance across all batches 
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LOCATIONS

Registered Office

10-A, First Floor, V.V Complex, Prakash Nagar, Thiruverumbur, Trichy-620013, Tamil Nadu, India.

Operations Office

9/1, Poonthottam Nagar, Ramanandha Nagar, Saravanampatti, Coimbatore-641035, Tamil Nadu, India. ㅤ

Other Locations

  • Bhilai
  • Chennai
  • India
  • Germany
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LOCATIONS

Registered Office

10-A, First Floor, V.V Complex, Prakash Nagar, Thiruverumbur, Trichy-620013, Tamil Nadu, India.

Other Locations

  • Bangalore
  • Chennai
  • India
  • Germany
Become a Frigatian
Become a Supplier

GENERAL ENQUIRIES

  • +91 96778 64606
  • manufacture@frigate.ai
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Long Weld Neck Flanges

Need reliable wires and cables for your next project? Get in touch with us today, and we’ll help you find exactly what you need!

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Long Weld Neck Flanges

Need reliable Machining for your next project? Get in touch with us today, and we’ll help you find exactly what you need!

Get Latest Price

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